Display device

ABSTRACT

In a display device that provides a first observation region with a first picture and provides a second observation region with a second picture, a double image made of the first picture and the second picture is suppressed. First columns of pixels that display the first picture and second columns of pixels that display the second picture are disposed alternately with a black matrix interposed between each neighboring pair of them. A light-shielding plate having light-shielding portions and openings is disposed above the panel. When a distance between the first observation region and the second observation region is denoted by V, a distance between the first observation region or the second observation region and the light-shielding plate is denoted by D, a distance between the light-shielding plate and the display panel is denoted by G, an interval of the first columns of pixels or the second columns of pixels is denoted by P, and the width of the black matrix is denoted by Q, an equation K≦Q×D/(D+G) is satisfied. The openings are disposed on lines connecting between a position directly above a center of the display panel and the black matrix.

CROSS-REFERENCE OF THE INVENTION

This application claims priority from Japanese Patent Application Nos.2006-085955 and 2006-085956, the contents of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a display device, specifically to a displaydevice that provides a first observation region with a first picture andprovides a second observation region with a second picture.

2. Description of the Related Art

A liquid crystal display device using a liquid crystal panel for display(hereafter referred to as an LCD (Liquid Crystal Display)) has beenknown as a display device incorporated in a TV receiver, informationequipment and the like. Relating to the display devices such as theliquid crystal display device, a dual picture display that provides afirst observation region with a first picture and provides a secondobservation region with a second picture, has come to be known, as theinformation equipment diversifies in recent years.

A dual picture display device according to a conventional art will bedescribed hereafter referring to the drawings. FIG. 12 is across-sectional view showing the display device according theconventional art. In the display device 100, there is disposed a displaypanel 10 that is made of first columns of pixels 10A that display thefirst picture and second columns of pixels 10B that display the secondpicture disposed alternately, as shown in FIG. 12. The first columns ofpixels 10A and the second columns of pixels 10B are made of pixels eachhaving a liquid crystal layer, for example. There is formed a so-calledblack matrix 11 between neighboring pixels in the first columns ofpixels 10A and the second columns of pixels 10B. A light-shielding plate50 made of metal or resin that has a light-shielding function isdisposed above the display panel 10 through a transparent substrate (notshown) such as a glass substrate. The light-shielding plate 50 isprovided with light-shielding portions 51 and openings 52 disposedalternately and extending parallel to the first columns of pixels 10Aand the second columns of pixels 10B.

Next, how the structure described above works to realize the dualpicture display will be explained. The first observation region A, whichis located to the left of a position C directly above a center of thedisplay panel 10, is provided with the first picture from the firstcolumns of pixels 10A through openings 52 in the light-shielding plate50, as shown in FIG. 12. At that time, the first observation region A isnot provided with the second picture from the second columns of pixels10B, because the light-shielding portions 51 in the light-shieldingplate 50 block the second picture.

On the other hand, the second observation region B, which is located tothe right of the position C directly above the center of the displaypanel 10, is provided with the second picture from the second columns ofpixels 10B through the openings 52 in the light-shielding plate 50. Atthat time, the second observation region B is not provided with thefirst picture from the first columns of pixels 10A, because thelight-shielding portions 51 in the light-shielding plate 50 block thefirst picture. As described above, there is performed the dual picturedisplay in which the first observation region A is provided with thefirst picture and the second observation region B is provided with thesecond picture.

Technologies mentioned above are disclosed in Japanese PatentApplication Publication No. 2005-258016.

With the dual picture display by the display device described above,however, there is caused a double image or an overlapping of the firstand second pictures when the display panel 10 is observed from theposition C directly above the center of the display panel 10 or itsvicinity. That is, the first picture can not be distinguished from thesecond picture, thus a quality of the dual picture display has suffered.

SUMMARY OF THE INVENTION

This invention is directed to suppress overlapping of a first pictureand a second picture in a display device that provides a firstobservation region with the first picture and provides a secondobservation region with the second picture.

This invention offers a display device, which provides a firstobservation region with a first picture and provides a secondobservation region with a second picture, including a display panel inwhich first columns of pixels that display the first picture and secondcolumns of pixels that display the second picture are disposedalternately with a black matrix interposed between each neighboring pairof them, and a light-shielding plate disposed above the display paneland including light-shielding portions and openings disposed alternatelyand extending parallel to the first columns of pixels and the secondcolumns of pixels, wherein the following equation is satisfied:K≦Q×D/(D+G)

where D is a distance between the light-shielding plate and the firstobservation region or the second observation region, G is a distancebetween the light-shielding plate and the display panel, K is a width ofeach of the openings and Q is a width of the black matrix. Thisinvention also offers the display device wherein the following equationis satisfied:P=G×V/D

where V is a width of the first observation region or the secondobservation region and P is an interval of the first columns of pixelsor the second columns of pixels. This invention also offers the displaydevice wherein the light-shielding portions are disposed so that a lineconnecting a position directly above a center of the display panel andthe black matrix goes through each of the openings.

This invention also offers a display device, which provides a firstobservation region with a first picture and provides a secondobservation region with a second picture, including a display panel inwhich first columns of pixels that display the first picture and secondcolumns of pixels that display the second picture are disposedalternately and a movable barrier that is disposed above the displaypanel, includes light-shielding portions and transmissive portionsdisposed alternately and extending in parallel to the first and secondcolumns of pixels, and is capable of changing locations of thelight-shielding portions and the transmissive portions. This inventionalso offers the display device further including a detector that detectsan orientation of the display panel and changing the locations of thelight-shielding portions and the transmissive portions in the movablebarrier in response to a result of detection by the detector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are plan views showing a display device according to anexample of a first embodiment of this invention.

FIG. 2 is a cross-sectional view showing the display device according tothe example of the first embodiment of this invention.

FIG. 3 is a conceptual drawing showing positioning relationship betweena black matrix in a display panel and an opening in a light-shieldingplate shown in FIG. 2.

FIGS. 4A and 4B are plan views showing a display device according toanother example of the first embodiment of this invention.

FIGS. 5A and 5B are plan views showing a display device according to anexample of a second embodiment of this invention.

FIG. 6 is a cross-sectional view showing the display device according tothe example of the second embodiment of this invention.

FIGS. 7A and 7B are cross-sectional views showing the display deviceaccording to the example of the second embodiment of this invention.

FIGS. 8A and 8B are conceptual drawings showing positioning relationshipbetween a display panel and a movable barrier shown in FIG. 6.

FIG. 9 is a cross-sectional view showing the display device according tothe example of the second embodiment of this invention.

FIGS. 10A and 10B are top views showing the display device according tothe example of the second embodiment of this invention.

FIGS. 11A and 11B are plan views showing a display device according toanother example of the second embodiment of this invention.

FIG. 12 is a cross-sectional view showing a display device according toa conventional art.

DETAILED DESCRIPTION OF THE INVENTION

A display device according to an example of a first embodiment of thisinvention will be described hereafter referring to the drawings. FIGS.1A and 1B are plan views showing the display device 1A according to theexample of the first embodiment of this invention. FIGS. 1A and 1B showa display panel 10 and a light-shielding plate 30 overlapping with it,respectively. Both of them will be described later. FIG. 2 is across-sectional view showing a section X-X in FIG. 1A. That is, FIG. 2shows a cross section that is orthogonal to first columns of pixels 10Aand second columns of pixels 10B, which are to be described later. InFIGS. 1A, 1B and 2, the same components as those in FIG. 12 are denotedby the same symbols.

In the display device 1A, there is disposed the display panel 10 that ismade of the first columns of pixels 10A that display a first picture andthe second columns of pixels 10B that display a second picture disposedalternately, as shown in FIGS. 1A and 2. Also, there is disposed aso-called black matrix 11 between neighboring pair of the first columnof pixels 10A and the second column of pixels 10B. The first columns ofpixels 10A and the second columns of pixels 10B are made of pixels eachhaving a liquid crystal layer, for example. The first columns of pixels10A and the second columns of pixels 10B are not limited to be made ofthe pixels having the liquid crystal layer, and may be made of otherpixels such as pixels having organic electroluminescent devices, forexample, as light-emitting devices.

The light-shielding plate 30 made of a metal or a resin and having alight-shielding function is disposed above the display panel 10 througha transparent substrate (not shown) such as a glass substrate. Thelight-shielding plate 30 is provided with light-shielding portions 31and openings 32 disposed alternately and extending parallel to the firstcolumns of pixels 10A and the second columns of pixels 10B.

A first observation region A, which is located to the left of a positionC directly above a center of the display panel 10, is provided with thefirst picture, while a second observation region B is located to theright of the position C directly above the center of the display panel10. The position C directly above the center of the display panel 10means a position on a line perpendicular to a plane parallel to thedisplay panel 10 and intersecting a line dividing approximately equallythe display panel 10 in a direction perpendicular to the first columnsof pixels 10A and the second columns of pixels 10B and its vicinity.

Next, detailed structures of the display panel 10 and thelight-shielding plate 30 will be described. Each of the light-shieldingportions 31 in the light shielding plate 30 are disposed in a way thateach of lines connecting between the position C directly above thecenter of the display panel 10 and the black matrix 11 goes throughcorresponding each of the openings 32.

A distance between the light-shielding plate 30 and either the firstobservation region A or the second observation region B is denoted by D.In this embodiment, this distance D is about 650 mm. A distance betweenthe light-shielding plate 30 and the display panel 10 is denoted by G. Awidth of the opening 32 in the light-shielding plate 30 is denoted by K,and a width of the black matrix 11 in the display panel 10 is denoted byQ. In this case, the display panel 10 and the light-shielding plate 30are formed so as to satisfy the following equation (1):K≦Q×D/(D+G)  (1)This equation (1) represents a condition that only the black matrix 11is observed through the openings 32 in the light-shielding plate 30 atthe position C directly above the center of the display panel 10 todisplay black.

However, if the width K of the opening 32 is decided to be extremelysmall, brightness of each of the first and second pictures looked ateach of the first and second observation regions A and B, respectively,would be too low to recognize the picture. Therefore, in this embodimentthe minimum value of the width K of the opening 32 is decided so as tomake the brightness high enough to cause no problem to recognize each ofthe first and second pictures at each of the first and secondobservation regions A and B.

Next, how the equation (1) is derived is explained referring to thedrawings. FIG. 3 is a conceptual drawing showing positioningrelationship between the black matrix 11 in the display panel 10 and theopening 32 in the light-shielding plate 30 shown in FIG. 2.

There is defined a triangle CLM (hereafter referred to as ΔCLM) havingthe width K of the opening 32 as a base and the position C as an apexopposite to the base, as shown in FIG. 3. Also, there is defined atriangle CST (hereafter referred to as ΔCST) having the width Q of theblack matrix 11 as a base and the position C as an apex opposite to thebase.

In order that only the black matrix 11 is observed through the opening32 at the position C directly above the center of the display panel 10,the width K of the opening 32 must take a value that makes the trianglesΔCLM and ΔCST geometrically similar to each other or the less. In thecase where the triangles ΔCLM and ΔCST are geometrically similar to eachother, a ratio of the width Q to the width K is equal to a ratio of alength of a side CS to a length of a side CL. At that time, the ratio ofthe length of the side CS to the length of the side CL is also equal toa ratio of a sum of the distance D and the distance G to the distance D.That is, when the triangles ΔCLM and ΔCST are geometrically similar toeach other, an equation (2) is derived:K:Q=D:(D+G)  (2)The value of the width K is obtained based on the equation (2). A rangeof the width K in which K is equal to or less than the obtained value isexpressed by the equation (1).

When a width of the first observation region A and the secondobservation region B is denoted by V and a pitch that is an interval ofthe first columns of pixels 10A as well as the second columns of pixels10B is denoted by P as shown in FIG. 2, the display panel 10 is formedso as to satisfy a following equation (3):P=G×V/D  (3)

The equation (3) is derived from a geometrical relationship representedby an equation (4):P:V=G:D  (4)

Next, how the structure described above works to realize the dualpicture display will be explained referring to the drawings. Neither thefirst picture in the first columns of pixels 10A nor the second picturein the second columns of pixels 10B is provided to the position Cdirectly above the center of the display panel 10 because both picturesare shielded by the light-shielding portions 31, as shown in FIG. 2.That is, because only the black matrix 11 is observed at the position Cdirectly above the center of the display panel 10, black is displayed.This is because the lines connecting the position C directly above thecenter of the display panel 10 and the black matrix 11 goes through theopenings 32 and because the equation (1) is satisfied. Although notshown in the figure, when a left hand side of the equation (1), i.e. thewidth K of the opening 32, is smaller than a right hand side of theequation (1), that is, when both sides of the equation (1) are not equalto each other, the region where black is displayed exists not only atthe position C directly above the center of the display panel 10 butalso in its vicinity.

The first picture is provided to the first observation region A from thefirst columns of pixels 10A through the openings 32 based on therelationship of the equation (3). At that time, the first observationregion A is not provided with the second picture displayed by the secondcolumns of pixels 10B, because the second picture is blocked by thelight-shielding portions 31.

On the other hand, the second picture is provided to the secondobservation region B from the second columns of pixels 10B through theopenings 32 based on the relationship of the equation (3). At that time,the second observation region B is not provided with the first picturedisplayed by the first columns of pixels 10A, because the first pictureis blocked by the light-shielding portions 31.

As described above, while the dual picture display is realized with thedisplay panel 10, the double image that is overlapping of the firstpicture and the second picture as observed with the conventional art canbe suppressed at the position C directly above the center of the displaypanel 10 and in its vicinity. As a result, the quality of the dualpicture display can be improved compared with the conventional art.

The display panel 10 and the light-shielding plate 30 in the embodimentis not limited to the structure described above, and may be disposed asdescribed below as long as it is as effective as described above. FIGS.4A and 4B are plan views showing a display device according to anotherexample of the first embodiment of this invention. FIGS. 4A and 4B showa display panel 10 and a light-shielding plate 30 overlapping with it,respectively.

Pixels in the first columns of pixels 10A and pixels in the secondcolumns of pixels 10B may be disposed alternately in every row andcolumn, as shown in FIG. 4A. In this case, the light-shielding portions31 and the openings 32 in the light-shielding plate 30G may be dividedcorresponding to the pixels in the first columns of pixels 10A and thepixels in the second columns of pixels 10B and disposed alternately inevery row and column, as shown in FIG. 4B. Visibility of the dualpicture can be thereby further improved because there are the first andsecond pictures existing alternately not only in terms of columns butalso in terms of rows.

Next, a display device according to an example of a second embodiment ofthis invention will be described hereafter referring to the drawings.FIGS. 5A and 5B are plan views showing the display device 1B accordingto the example of the second embodiment of this invention. FIGS. 5A and5B show a display panel 10 and a movable barrier 40 overlapping with it,respectively. Both of them will be described later. FIG. 6 is across-sectional view showing a section X-X in FIG. 5A. That is, FIG. 6shows a cross section that is orthogonal to first columns of pixels 10Aand second columns of pixels 10B, which are to be described later. FIG.6 shows a case in which locations of transmissive portions in themovable barrier 40 are in a first state that is to be described later.In FIGS. 5A, 5B and 6, the same components as those in FIG. 12 aredenoted by the same symbols.

In the display device 1B, there is disposed the display panel 10 made ofthe first columns of pixels 10A, which display a first picture, and thesecond columns of pixels 10B, which display a second picture, disposedalternately as shown in FIGS. 5A and 6. Also, there is disposed aso-called black matrix 11 between neighboring pair of the first columnof pixels 10A and the second column of pixels 10B. The first columns ofpixels 10A and the second columns of pixels 10B are made of pixels eachhaving a liquid crystal layer, for example. The first columns of pixels10A and the second columns of pixels 10B are not limited to be made ofthe pixels having the liquid crystal layer, and may be made of otherpixels such as pixels having organic electroluminescent devices, forexample, as light-emitting devices.

A first observation region A, that is provided with the first picture,is located to the left of a position C1 directly above a center of thedisplay panel 10, while a second observation region B, that is providedwith the second picture, is located to the right of the position C1directly above the center of the display panel 10. The position C1directly above the center of the display panel 10 means a position on aline perpendicular to a plane parallel to the display panel 10 andintersecting a line approximately equally dividing the display panel 10in a direction perpendicular to the first columns of pixels 10A and thesecond columns of pixels 10B and its vicinity.

Between the display panel 10 and the first and second observationregions A and B, a movable barrier 40 is disposed above the displaypanel 10 through a transparent substrate such as a glass substrate (notshown). The movable barrier 40 has light-shielding portions andtransmissive portions disposed alternately and extending in parallel tothe first columns of pixels 10A and the second columns of pixels 10B.The movable barrier 40 is capable of changing locations of thelight-shielding portions and the transmissive portions, as will bedescribed later. The first observation region A and the secondobservation region B can be moved by changing the locations of thetransmissive portions in the movable barrier 40.

A structure of the movable barrier 40 will be described hereafter,referring to the drawings. FIGS. 7A and 7B are magnified cross-sectionalviews of the movable barrier 40 shown in FIG. 6. FIG. 7A shows the casein which the locations of the transmissive portions in the movablebarrier 40 are in the first state, while FIG. 7B shows a case in whichthe locations of the transmissive portions in the movable barrier 40 arein a second state.

The movable barrier 40 is a liquid crystal barrier made of a firsttransparent substrate 42A having a first polarizing plate 41A, a secondtransparent substrate 42B having a second polarizing plate 41B and aliquid crystal layer LC interposed between the two transparentsubstrates 42A and 42B, as shown in FIGS. 6 and 7A. The firsttransparent substrate 42A and the second transparent substrate 42B aremade of glass substrates, for example. And the movable barrier 40 isformed to be of normally white type that passes light when there is noelectric field in the liquid crystal layer LC.

A plurality of first transparent electrodes 43 extending parallel to thefirst columns of pixels 10A and the second columns of pixels 10B isdisposed at regular intervals on the first transparent substrate 42A.Also on the first transparent substrate 42A, there are disposed a secondtransparent electrode 44 isolated from the first transparent electrode43 along one edge of each of the first transparent electrodes 43 and athird transparent electrode 45 isolated from the first transparentelectrode 43 along another edge of each of the first transparentelectrodes 43.

A fourth transparent electrode 46, to which a common electric potentialis provided, is disposed on the second transparent substrate 42B. Thefirst through fourth transparent electrodes 43, 44, 45 and 46 are madeof transparent metal such as ITO (Indium Tin Oxide).

And the movable barrier 40 is connected with a control circuit CNT thatcontrols applying voltage so that the liquid crystal layer LC above thefirst transparent electrodes 43 is rendered non transmissive and theliquid crystal layer LC above either the second transparent electrodes44 or the third transparent electrodes 45 is rendered non transmissiveas well.

When the movable barrier 40 is in the first state, the control circuitCNT controls so that the liquid crystal layer LC above the firsttransparent electrodes 43 and the liquid crystal layer LC above thesecond transparent electrodes 44 are rendered non transmissive, as shownin FIG. 7A. That is, a voltage is applied from the control circuit CNTto the first transparent electrodes 43 and the second transparentelectrodes 44, while the fourth transparent electrode 46 is providedwith the common electric potential. As a result, the electric field iscaused in the liquid crystal layer LC above the first transparentelectrodes 43 and above the second transparent electrodes 44, andalignment of liquid crystal molecules in the liquid crystal layer LC ischanged along the electric field to change their opticalcharacteristics. In the movable barrier 40, at that time, the liquidcrystal layer LC above the first transparent electrodes 43 and above thesecond transparent electrodes 44 make light-shielding portions in thefirst state, and regions other than the light-shielding portions maketransmissive portions 47A in the first state.

On the other hand, when the movable barrier 40 is in the second state,the control circuit CNT controls so that the liquid crystal layer LCabove the first transparent electrodes 43 and the liquid crystal layerLC above the third transparent electrodes 45 are rendered nontransmissive, as shown in FIG. 7B. That is, the voltage is applied fromthe control circuit CNT to the first transparent electrodes 43 and thethird transparent electrodes 45, while the fourth transparent electrode46 is provided with the common electric potential. As a result, anelectric field is caused in the liquid crystal layer LC above the firsttransparent electrodes 43 and above the third transparent electrodes 45.The alignment of liquid crystal molecules in the liquid crystal layer LCis changed along the electric field to change their opticalcharacteristics. In the movable barrier 40, at that time, the liquidcrystal layer LC above the first transparent electrodes 43 and above thethird transparent electrodes 45 make light-shielding portions in thesecond state and regions other than the light-shielding portions maketransmissive portions 47B in the second state.

Positioning relationship between the display panel 10 and components inthe movable barrier 40 is described hereafter. A width of each of thefirst and second observation regions A and B is denoted by V, as shownin FIG. 6. A moving distance of each of the first and second observationregions A and B between the first state and the second state is set tobe V/2. A distance between the movable barrier 40 and either the firstobservation region A or the second observation region B is denoted by D.A distance between the movable barrier 40 and the display panel 10 isdenoted by G. An interval of the first columns of pixels 10A as well asthe second columns of pixels 10B is denoted by P.

A width of each of the second and third transparent electrodes 44 and 45is denoted by S, as shown in FIGS. 7A and 7B. To be precise, the width Sis defined as a distance from an edge of the first transparent electrode43 to an edge of a neighboring second transparent electrode 44 or aneighboring third transparent electrode 45. The width S is a movingdistance of the light-shielding portions and the transmissive portionsin the movable barrier 40. R denotes an interval of sets, each of whichis made of neighboring one each of the first transparent electrodes 43,the second transparent electrodes 44 and the third transparentelectrodes 45. In this case, the display panel 10 and the movablebarrier 40 are formed so as to satisfy a following equation (5):S≦R/4  (5)

Next, how the equation (5) is derived is explained referring to thedrawings. FIGS. 8A and 8B are conceptual drawings showing thepositioning relationship between the display panel 10 and the movablebarrier 40 shown in FIG. 6.

There is defined a triangle HJK (hereafter referred to as ΔHJK) having2P that is a sum of the interval of the first columns of pixels 10A andthe interval of the second columns of pixels 10B as a base and aposition H that is in the first observation region A or in the secondobservation region B as an apex vertically facing to the base, as shownin FIG. 8A. Also, there is defined a triangle HIL (hereafter referred toas ΔHIL) having R that is the interval of the sets, each of which iscomposed of the first transparent electrode 43, the second transparentelectrode 44 and the third transparent electrode 45, as a base and theposition H as an apex vertically facing to the base.

In order for the first picture or the second picture to be observedthrough the transparent portions 47A in the first state of the movablebarrier 40 or through the transparent portions 47B in the second state,it is necessary that the triangles ΔHJK and ΔHIL are geometricallysimilar to each other. In the case where the triangles ΔHJK and ΔHIL aregeometrically similar to each other, a ratio of 2P to R is equal to aratio of a length of a side HJ to a length of a side HI. And the lengthof the side HI is equal to the distance D, and the length of the side HJis equal to a sum of the distance D and the distance G. That is, whenthe triangles ΔHJK and ΔHIL are geometrically similar to each other, anequation (6) is derived:R:2P=D:(D+G)  (6)

There is defined a triangle JHO (hereafter referred to as ΔJHO) havingV/2, which is the moving distance of the first observation region A andthe second observation region B, as a base and a position J, which is inthe first columns of pixels 10A or in the second columns of pixels 10B,as an apex vertically facing to the base, as shown in FIG. 8B. Also,there is defined a triangle JMN (hereafter referred to as ΔJMN) havingthe width S as a base and the position J as an apex vertically facing tothe base.

In order for the first picture or the second picture to be observed in arange of the moving distance V/2 of the first observation region A andthe second observation region B, the width S needs to take a value thatmakes the triangles ΔJHO and ΔJMN geometrically similar to each other.

In the case where the triangles ΔJHO and ΔJMN are geometrically similarto each other, a ratio of the moving distance V/2 to the width S isequal to a ratio of a length of a side JH to a length of a side JM. Andthe length of the side JM is equal to the distance G, and the length ofthe side JH is equal to a sum of the distance D and the distance G. Thatis, when the triangles ΔJHO and ΔJMN are geometrically similar to eachother, an equation (7) is derived:S:V/2=G:(D+G)  (7)

In order for the first picture or the second picture to be observed inthe first observation region A or in the second observation region B,respectively, the display panel 10 is to be formed to satisfy anequation (8):P:V=G:D  (8)

Solving the equations (6), (7) and (8) with respect to S gives anequation (9):S=R/4  (9)

In the above explanation, the moving distance of the first observationregion A and the second observation region B has been set to V/2.However, the moving distance does not need to be larger than V/2 whenthe first observation region A and the second observation region B aremoved to suppress the double image at the position C directly above thecenter of the display panel 10. That is, the moving distance is equal toor less than V/2. The equation (5) is obtained by reflecting the abovein the equation (9).

Next, how the structure described above works to realize the dualpicture display will be explained referring to FIGS. 6 and 9. FIG. 9,like as FIG. 6, is a cross-sectional view showing the section X-X inFIG. 5. However, FIG. 9 shows the case in which the locations of thetransmissive portions in the movable barrier 40 are in the second state.

At first, the first state is explained. The first observation region Ais provided with the first picture from the first columns of pixels 10Athrough the transmissive portions 47A in the movable barrier 40 in thefirst state, as shown in FIG. 6. At that time, the second picture fromthe second columns of pixels 10B is not provided to the firstobservation region A because it is blocked by the light-shieldingportions in the movable barrier 40, that is, the liquid crystal layer LCabove the first transparent electrodes 43 and above the secondtransparent electrodes 44.

On the other hand, the second observation region B is provided with thesecond picture from the second columns of pixels 10B through thetransmissive portions 47A in the movable barrier 40 in the first state.At that time, the first picture from the first columns of pixels 10A isnot provided to the second observation region B because it is blocked bythe light-shielding portions in the movable barrier 40. As describedabove, there is performed the dual picture display in which the firstobservation region A is provided with the first picture and the secondobservation region B is provided with the second picture. However, thedouble image made of the first picture and the second picture isobserved at the position C1 directly above the center of the displaypanel 10.

Next, the second state is explained. As shown in FIG. 9, thetransmissive portions 47B in the movable barrier 40 in the second stateare moved to the right compared with the transmissive portions 47A inthe first state. Since the light-shielding portions in the second stateare above the first transparent electrodes 43 and above the thirdtransparent electrodes 45, they are also moved to the right comparedwith the light-shielding portions in the first state.

Because the first picture and the second picture passing through thetransmissive portions 47B are thereby provided to the right comparedwith the first state, the first observation region A and the secondobservation region B are moved to the right by the distance V/2. Thatis, the position C1 directly above the center of the display panel 10 isnow in the first observation region A which is provided with the firstpicture, and the double image as observed in the first state is nolonger observed. In other words, the first observation region A and thesecond observation region B can be moved by switching between the firststate and the second state.

Furthermore, in this embodiment, the movable barrier 40 may becontrolled by the control circuit CNT so that the liquid crystal layerLC above the first transparent electrodes 43, above the secondtransparent electrodes 44 and above the third transparent electrodes 45becomes transmissive in a state other than the first and second statesdescribed above. In this case, the whole movable barrier 40 works simplyas a transmissive plate. At that time, by making the first picture andthe second picture a common picture, a single picture display in whichthe single common picture is provided to both the first observationregion A and the second observation region B can be performed. There isno light-shielding portion in the movable barrier 40 in this case. Thus,the single picture display can be realized without reducing brightnesscompared with a case in which the single picture display is realized bymaking the first picture and the second picture a common picture in thedual picture display state.

In the dual picture display described above, the first picture and thesecond picture can be switched arbitrarily. Instead, the first pictureand the second picture may be switched automatically in response to anorientation of the display panel 10 as described below. FIGS. 10A and10B are top views showing a display device according to the example ofthe second embodiment of this invention. Positioning relationshipbetween the display device 1B and the first and second observationregions is viewed from above. FIG. 10A corresponds to the first statewhile FIG. 10B corresponds to the second state.

A detector DTC that detects the orientation of the display device 1B isconnected with the display device 1B, as shown in FIG. 10A. Neither afirst observer OB1 nor a second observer OB2 is at the position C1directly above the display panel 10 in the first state. The firstobserver OB1 is in the first observation region A and observes the firstpicture. And the second observer OB2 is in the second observation regionB and observes the second picture.

When the orientation of the display panel 10 is turned to place thefirst observer OB1 at the position C1 directly above the center of thedisplay panel 10 as shown in FIG. 10B, the first observer OB1 comes toobserve the double image made of the first picture and the secondpicture.

Thus, the detector DTC detects an angle θ corresponding to a change inthe orientation of the display panel 10 to switch to the second state.And in response to a result of the detection by the detector DTC, thecontrol circuit CNT switches from the transmissive portions 47A in themovable barrier 40 in the first to the transmissive portions 47B in thesecond state. At that time, the control circuit CNT controls the liquidcrystal layer LC above the first transparent electrodes 43, above thesecond transparent electrodes 44 and above the third transparentelectrodes 45 in the movable barrier 40 as described above. As a result,the first observer OB1 at the position C1 directly above the center ofthe display panel 10 comes to be placed in the first observation regionA after changing the state and be able to observe the first picture.

Also, switching between the dual picture display and the single picturedisplay may be executed in response to the orientation of the displaypanel 10. In this case, transmissiveness of the liquid crystal layer LCabove the first transparent electrodes 43, the second transparentelectrodes 44 and the third transparent electrodes 45 is controlled bythe control circuit CNT according to the result of the detection by thedetector DTC.

The display panel 10 and the first, second and third transparentelectrodes 43, 44 and 45 are not limited to the structures shown inFIGS. 5A and 5B, and may be structured as described below, as long asthey are as effective as those described above. FIGS. 11A and 11B areplan views showing a display device according to another example of thesecond embodiment of this invention. FIG. 11A and FIG. 11B show thedisplay panel 10 and sets of the first, second and third transparentelectrodes 43, 44 and 45 in a movable barrier 40G overlapping thedisplay panel 10, respectively.

Pixels in the first columns of pixels 10A and pixels in the secondcolumns of pixels 10B may be disposed alternately in every row andcolumn, as shown in FIG. 11A. In this case, the sets of the first,second and third transparent electrodes 43, 44 and 45 and regions whereno transparent electrodes are formed in the movable barrier 40G may bedivided corresponding to the pixels in the first columns of pixels 10Aand the pixels in the second columns of pixels 10B and disposedalternately in every row and column, as shown in FIG. 11B. Visibility ofthe dual picture can be thereby further improved because there are thefirst and second pictures existing alternately not only in terms ofcolumns but also in terms of rows.

If there is no need for the single picture display described above, theliquid crystal layer LC above the first transparent electrodes 43 in themovable barrier 40 or 40G does not need to become transmissive in thisembodiment. In this case, light-shielding layers made of non-transparentmetallic or nonmetallic material that always shield light may be formedinstead of the first transparent electrodes 43.

Although the movable barrier 40 or 40G is described in the embodiment asbeing structured so that the transmissive portions 47B in the secondstate is moved to the right compared with the transmissive portions 47Ain the first state, the embodiment is not limited to the above. That is,the movable barrier 40 or 40G may be structured so that the transmissiveportions 47B in the second state are moved to the left compared with thetransmissive portions 47A in the first state.

Also, although the movable barrier 40 or 40G is described in theembodiment as being formed to be of normally white type, the embodimentis not limited to the above. That is, the movable barrier 40 or 40G maybe formed to be of normally black type.

And although the movable barrier 40 or 40G is described in theembodiment as the liquid crystal barrier, the embodiment is not limitedto the above. That is, the movable barrier 40 or 40G may not be theliquid crystal barrier as long as the light-shielding portions and thetransmissive portions are moved so as to produce the effect as describedabove.

With the display devices according to the embodiments, which provide thefirst observation region with the first picture and the secondobservation region with the second picture, the double image made of thefirst picture and the second picture is suppressed to improve thequality of the display compared with the conventional art, when thedisplay panel is observed from the position directly above the center ofthe display panel.

In addition, locations of the first observation region and the secondobservation region can be changed in response to the orientation of thedisplay panel.

1. A display device configured to provide a first observation regionwith a first picture and a second observation region with a secondpicture, comprising: a display panel comprising first pixelscollectively providing the first picture and second pixels collectivelyproviding the second picture, the first and second pixels forming amatrix; a light-manipulating plate disposed above the display panel andcomprising elongated light-passing portions extending in a direction ofcolumns of the matrix and light-manipulation portions disposed alongcorresponding elongated light-passing portions, the light-manipulationportions being configured to alternate between a light shielding stateand a light transmission state; and a control circuit, wherein thelight-manipulating plate comprises a first transparent substrate, asecond transparent substrate, a liquid crystal layer interposed betweenthe first and second transparent substrates, a plurality of firsttransparent electrodes disposed on the first substrate and extending inthe direction of the columns of the matrix, a second transparentelectrode extending along a side of each of the first transparentelectrodes, a third transparent electrode extending along another sideof each of the first transparent electrodes and a fourth transparentelectrode disposed on the second transparent substrate, and the controlcircuit controls the light-manipulating plate so that the liquid crystallayer above the first transparent electrodes does not allow light topass and the liquid crystal layer above either the second transparentelectrodes or the third transparent electrodes does not allow light topass, wherein the following relationship is satisfied;S≦R/4 where S is a width of the second transparent electrode or thethird transparent electrode and R is an interval of the firsttransparent electrodes.
 2. The display device of claim 1, furthercomprising a detector configured to detect an orientation of the displaypanel, wherein the light-manipulation portions is configured to change,in response to a detection by the detector, from the light shieldingstate to the light transmission state or from the light transmissionstate to the light shielding state.
 3. The display device of claim 1,wherein the light-manipulating plate comprises a liquid crystal layer.4. The display device of claim 1, further comprising a detectorconfigured to detect an orientation of the display panel, wherein thelight-manipulation portions is configured to change, in response to adetection by the detector, from the light shielding state to the lighttransmission state or from the light transmission state to the lightshielding state.
 5. The display device of claim 1, wherein the controlcircuit controls the light-manipulating plate so that the liquid crystallayer above the first transparent electrodes, the liquid crystal layerabove the second transparent electrodes and the liquid crystal layerabove the third transparent electrodes allow light to pass.
 6. A displaydevice configured to provide a first observation region with a firstpicture and a second observation region with a second picture,comprising: a display panel comprising first pixels collectivelyproviding the first picture and second pixels collectively providing thesecond picture, the first and second pixels forming a matrix; alight-manipulating plate disposed above the display panel and comprisingelongated light-passing portions extending in a direction of columns ofthe matrix and light-manipulation portions disposed along correspondingelongated light-passing portions, the light-manipulation portions beingconfigured to alternate between a light shielding state and a lighttransmission state; and a control circuit, wherein thelight-manipulating plate comprises a first transparent substrate, asecond transparent substrate, a liquid crystal layer interposed betweenthe first and second transparent substrates, a plurality oflight-shielding layers disposed on the first substrate and extending inthe direction of the columns of the matrix, a first transparentelectrode extending along a side of each of the light-shielding layers,a second transparent electrode extending along another side of each ofthe light-shielding layers and a third transparent electrode disposed onthe second transparent substrate, and the control circuit controls thelight-manipulating plate so that the liquid crystal layer above thefirst transparent electrodes does not allow light to pass or the liquidcrystal layer above the second transparent electrodes does not allowlight to pass, and wherein the following relationship is satisfied;S≦R/4 where S is a width of the first transparent electrode or thesecond transparent electrode and R is an interval of the firsttransparent electrodes.
 7. The display device of claim 6, furthercomprising a detector configured to detect an orientation of the displaypanel, wherein the light-manipulation portions is configured to change,in response to a detection by the detector, from the light shieldingstate to the light transmission state or from the light transmissionstate to the light shielding state.
 8. The display device of claim 1,wherein the first and second pixels are alternated in every column andevery row of the matrix, and sets of the first transparent electrodes,the second transparent electrodes and the third transparent electrodesof one row is shifted in a direction of the rows with respect to sets ofthe first transparent electrodes, the second transparent electrodes andthe third transparent electrodes of another row that is next to said onerow.
 9. The display device of claim 6, wherein the first and secondpixels are alternated in every column and every row of the matrix, andsets of the light-shielding layers, the first transparent electrodes andthe second transparent electrodes of one row is shifted in a directionof the rows with respect to sets of the light-shielding layers, thefirst transparent electrodes and the second transparent electrodes ofanother row that is next to said one row.
 10. The display device ofclaim 1, wherein every two columns of the matrix comprise only the firstpixels, other columns of the matrix comprise only the second pixels, andthe elongated light-passing portions have a length enough to cover alength of the columns.
 11. The display device of claim 6, furthercomprising a detector configured to detect an orientation of the displaypanel, wherein the light-manipulation portions is configured to change,in response to a detection by the detector, from the light shieldingstate to the light transmission state or from the light transmissionstate to the light shielding state.
 12. The display device of claim 6,wherein the light-manipulating plate comprises a liquid crystal layer.13. The display device of claim 6, wherein every two columns of thematrix comprise only the first pixels, other columns of the matrixcomprise only the second pixels, and the elongated light-passingportions have a length enough to cover a length of the columns.